Chemically diverse antimicrobials from silent biosynthetic pathways

描述(由申请人提供)：医疗保健相关感染(HAI)对美国人民的个人和经济福祉构成巨大威胁。在过去十年中，由于几个复合因素(例如，微生物抗药性水平的提高、免疫功能受损患者数量的增加以及新抗菌剂产量的急剧下降)，人类免疫缺陷病毒的死亡率激增。因此，迫切需要开发新的抗真菌和抗菌治疗药物来阻止人类免疫缺陷病毒造成的生命损失。不幸的是，许多现代药物筛选计划依赖于化学贫乏的文库，这严重损害了它们各自的先导发现潜力。许多这些化学库的一个主要缺点是化合物的同质性程度很高，并且它们的组成化合物之间缺乏结构新颖性。这项应用的目的是使用化学表观遗传学方法来批判性地检查由真菌中沉默的生物合成途径编码的独特的次生代谢物，作为新型抗菌剂的来源。我们将测试核心假设，即真菌中沉默的天然产物基因簇的激活将提供无与伦比的途径，获得化学上多样化的次生代谢物，我们将利用这些次生代谢物来获得新的抗菌和抗真菌线索。研究生产抗菌剂的沉默生物合成途径的基本原理是，从这一来源产生的次生代谢物在结构和功能上都有望是新的，因此这些化合物有望具有重要的药物开发价值。基于我们研究组强大的初步数据，我们设计了三个具体目标来检验中心假设：1)调查化学表观遗传修饰后从真菌中产生的抗菌活性的范围，2)使用生物测定引导的微孔板分离与电喷雾电离飞行时间质谱学相结合的方法来去复制和纯化生物活性天然产品，以测试一组微生物病原体，以及3)应用生物系统和半合成技术的组合来探索PI实验室中先前发现的两组独特的抗菌剂先导化合物的结构活性特征。这项研究意义重大，因为它利用了一种创新的方法--化学表观遗传学，从真菌中获得神秘的天然产品。这些化合物代表了一种尚未开发的生物活性有机分子来源，具有出色的治疗应用。预计这些研究将提供一系列化学上前所未有的天然产品，作为NIH赞助的未来研究的一部分，这些产品将具有极高的铅开发潜力。 公共卫生相关性：这些研究旨在解决治疗各种微生物病原体的新的抗菌和抗真菌药物的需求。这项工作很重要，因为从沉默的生物合成途径产生的真菌次生代谢物代表了一个尚未开发的化学多样性物质的储存库，这些物质具有巨大的治疗开发潜力。将这些结构不同的化合物注入药物发现管道中，有望为人类健康提供丰富的新来源，为抗击各种细菌和真菌疾病提供新的新来源。

DESCRIPTION (provided by applicant): Healthcare-associated infections (HAIs) pose a tremendous threat to the personal and financial wellbeing of the American people. Over the last decade, there has been a surge in mortality due to HAIs as a result of several compounding factors (e.g., increased levels of drug resistance among microbes, escalating numbers of immunocompromised patients, and a sharp decline in the production of new antimicrobials). Consequently, there is a critical need for the development of new antifungal and antibacterial therapeutics to stem the loss of human life caused by HAIs. Unfortunately, many modern drug screening programs rely on chemically impoverished libraries that severely compromise their respective lead discovery potentials. A major shortcoming for many of these chemical libraries is the significant degree of compound homogeneity and a lack of structural novelty among their component compounds. The objective of this application is to use a chemical-epigenetics methodology to critically examine the unique secondary metabolites that are encoded by silent biosynthetic pathways in fungi as a source of novel antimicrobials. We will test the central hypothesis that the activation of silent natural-product gene clusters in fungi will provide unparalleled access to chemically diverse secondary metabolites, which we will use for procuring new antibacterial and antifungal leads. The rationale for investigating silent biosynthetic pathways for the production of antimicrobials is that secondary metabolites emerging from this source are expected to be structurally and functionally novel; thus these compounds are anticipated to have significant drug development value. Based on our research group's strong preliminary data, three specific aims have been designed to test the central hypothesis: 1) investigate the range of antimicrobial activities emerging from fungi following chemical-epigenetic modification, 2) use bioassay-guided microplate fractionation in tandem with electrospray-ionization time-of-flight mass spectrometry to dereplicate and purify bioactive natural products for testing against a panel of microbial pathogens, and 3) apply a combination of biosystematic and semisynthetic techniques to probe the structure- activity features of two unique groups of antimicrobial leads previously discovered in the PI's laboratory. This research is significant because it capitalizes on an innovative methodology, chemical epigenetics, to access cryptic natural products from fungi. These compounds represent an untapped source of bioactive organic molecules with outstanding therapeutic applications. It is anticipated that these studies will provide an array of chemically unprecedented natural products that will have superb lead development potential as part of future NIH-sponsored studies. PUBLIC HEALTH RELEVANCE: These studies are designed to address the need for new antibacterial and antifungal agents for treating a wide range of microbial pathogens. This work is important because fungal secondary metabolites produced from silent biosynthetic pathways represent an untapped reservoir of chemically diverse substances that have immense potential for therapeutic development. The infusion of these structurally diverse compounds into the drug discovery pipeline is expected to have a significant positive impact on human health by providing a rich new source of novel small-molecule leads for combating a variety of bacterial and fungal illnesses.